doubt in classpath

[Srividhya Kiran]

I have the following directory structure

[B]
  bin
   |--DirA
        |--A.java
        |--DirB
           |--B.java
           |--DirC
              |--C.java[/B]

My Current Directory is DirA. when I give

c:\DirA>javac - cp DirB B.java

Compiler says error cant read B.java. But when I use -cp with java, i am getting the o/p of the B.java.

c:\DirA>java -cp DirB B

what is the problem here??

Thanks
Srividhya

[marc weber]

When you invoke javac, you need to provide a Java source file to be compiled. So from DirA, you can use...

javac DirB/B.java

It does not work when you try...

javac -cp DirB B.java

...because this is telling javac to compile B.java from the current directory (DirA), which fails because that's not where B.java is. The classpath flag only tells Java to find any additional classes it needs under DirB.

So from DirA, if you wanted to specify a classpath of DirB and compile B.java, you could use...

javac -cp DirB DirB/B.java

(PS: Are you sure you want to put your own subdirectories under a "bin" directory?)

[Srividhya Kiran]

Marc can you explain more on this statement

c:/DirA>javac -cp DirB DirB/B.java

here does it mean it will look for class file under DirB, if so what are the class file it will look for. Then it will compile B.java which is under DirB.

C:/DirA>java -cp DirB/B why cant we give like this, even this means look for B class file under DirB directory right???

Sorry if I am disturbing you asking the same question.

Srividhya

[marc weber]

Sorry if I was confusing. I was just trying to show the difference between specifying a classpath and providing a path to the file you want to compile. So if you needed to do both, it could be done like this...

C:/DirA>javac -cp DirB DirB/B.java
              |      | |_________|
              |      |   path of file to compile: DirB/B.java
              |______|
                classpath for additional classes: DirB

But in your case, you probably don't need a classpath, so you can just use...

C:/DirA>javac DirB/B.java

As for the second part of your question, C:/DirA>java -cp DirB/B will not work because you are not telling Java what class to run. All you are doing is providing a classpath of "DirB/B", where "B" would be interpreted as another directory.

[Srividhya Kiran]

Thanks Marc for patiently clarifying my doubt I understood.